We discuss this in my Discord a lot. Real flying is a lot different with all the sights, smells, sounds, kinesthetic sense/proprioception, and control pressures in an environment that’s actually hazardous and can’t be paused.
Most folks can manipulate the controls and fly an airplane through the air with little or no coaching, so in a couple of hours, especially with an instructor, a person with sim experience should be getting close to a “manipulating the controls proficiently” portion of soloing, which isn’t far off from the hours person who began with no experience would need.
Whether or not it can be done proficiently without that instruction depends on a few things: whether you’ve learned how to do things correctly in the sim or not, which maneuvers or phase of flight we’re talking about, and the definition of “proficiently.”
Some common errors sim pilots make when transitioning from the sim world are how to correctly use trim, understanding the relationship between pitch and power (namely, climbing or descending at an airspeed versus a rate (including transitioning to/from level flight), and the biggie, relying too much on the gauges versus looking outside for references, traffic, and obstructions.
A lot people who consider themselves serious simmers haven’t had any feedback as to whether what they’re doing meets proficiency standards. So while a person may be able to steer the plane toward a runway pretty well, that’s a small portion of what we do. Amp it up a bit: can they do the same while safely entering a traffic pattern, avoiding other aircraft (plus obstructions and airspace), communicating, and configuring the plane for landing? And staying within standards the entire time? With a little coaching, it won’t be too long, without, I think you’d be surprised at how quickly people get behind the airplane. Even people who have been flying for a long time, or have been taking lots of lessons deal with this.
In the end, does simming give an advantage? Probably, in a couple of specific areas. Can some things become areas of negative transfer if they were learned incorrectly, which then take additional time to rectify? Probably that as well.
Here’s a link to an old thread where I opine as to what the sim doesn’t do well: